下颌阻生第三磨牙分段切割拔除术的选择

目的 探讨用涡轮机分段切割法拔除下颌中、低位阻生的第三磨牙的效果及适应证。方法 对481例675颗曲面体层片显示中、低位阻生的下颌第三磨牙用涡轮机分段切割法拔除。其中327颗实施二段切割法;348颗实施三段切割法。结果 下颌阻生第三磨牙均完全拔除;手术时间5~20 min（平均16 min）;术后发生短暂下唇麻木症状3例（3颗）,发生术后感染15例（15颗）。结论 二段切割法适用于中位近中阻生的下颌第三磨牙,三段切割法适用于中/低位近中、水平阻生的下颌第三磨牙。     

236颗下颌阻生第三磨牙锥形束CT影像的观察分析

[摘要] 目的 探讨锥形束CT(CBCT)三维重建技术用于分析阻生下颌第三磨牙的应用。方法 对下颌阻生第三磨牙的136例(236颗牙)患者CBCT影像资料利用NNT图像分析软件通过容积再现、多层面重建和曲面重建等技术对第三磨牙阻生情况进行分类统计。结果 236颗阻生下颌第三磨牙:高位垂直阻生最多(102颗),占43.22%,颊向阻生最少(1颗);15.68%与下颌神经管接触;与邻牙间隙>0、=0和<0分别为115、75和46颗;26.69%邻牙有龋坏;42.80%造成邻牙远中牙槽骨吸收。结论 CBCT扫描技术和分析软件的应用可提供下颌阻生第三磨牙位置的准确数据,为拔除手术方案的制定提供客观依据。     

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目的探讨三段式横断法拔除下颌低位水平阻生智齿对邻牙的影响。方法收集2008年7月至2009年12月中山大学光华口腔医学院附属口腔医院收治的下颌双侧低位水平阻生牙患者62例,共124颗牙。将患者左右侧阻生牙随机分成A、B两组,每组62颗。A组采用三段式横断法拔除阻生牙,B组采用两段式横断法拔除阻生牙。比较两组术后1周邻牙温度敏感、叩痛及松动等不良反应发生情况。结果术后1周,A组患者邻牙的温度敏感、叩痛及松动等不良反应的发生率均明显低于B组患者,差异均有统计学意义(P<0.05)。结论在拔除下颌低位水平阻生牙时,三段式横断法可以减少邻牙术后不良反应的发生,是一种值得在临床中推广的拔牙术式。     

Do pathologies associated with impacted lower third molars justify prophylactic removal? A critical review of the literature

Surgical removal of impacted lower third molars is widely carried out in general dental practice and in many institutional clinics. Despite the fact that there are well established indications for the removal of impacted lower third molars, prophylactic removal of these teeth is still being universally practiced. Some reports have estimated that the proportion of impacted third molars that are removed when no clinically sound justification for surgery is present is between 18% and 50.7%. Justifications for prophylactic surgery include the need to minimize the risk of disease (cysts and tumors) development, reduction of the risk of mandibular angle fracture, increased difficulty of surgery with age, and that third molars have no definite role in the mouth. This article critically examines the literature regarding the relationship between impacted lower wisdom teeth, cysts and tumor development, and mandibular fractures.     

下颌智齿阻生类型及其邻牙远中邻面患龋情况的对称性初探

目的 调查下颌第三磨牙生长情况的对称性及其对相邻第二磨牙远中邻面龋患病情况的影响,为临床早期预防性拔除下颌智齿提供依据。方法 纳入2019年11月1日至2019年11月23日在上海交通大学医学院附属仁济医院口腔科拍摄的全景片196张,调查其双侧下颌第三磨牙的对称性,通过卡方检验分析不同阻生类型的下颌第三磨牙与相邻第二磨牙远中邻面龋患病情况之间的关系。结果 双侧下颌第三磨牙对称者187例,占比95.41%。Winter分类中垂直阻生对称性（79.2%）显著高于近中阻生（47.6%）与水平阻生（59.1%）（P=0.001）; Winter分类为近中阻生（46.4%）和水平阻生（38.4%）的下颌第三磨牙,其相邻第二磨牙远中邻面龋发生率显著高于垂直阻生（23.6%）（P=0.001）。结论 下颌智齿具有对称性;为预防相邻第二磨牙远中邻面龋,近中阻生及水平阻生的下颌第三磨牙应在临床上早期预防性拔除。     

Third molar outcomes from age 18 to 26: findings from a population-based New Zealand longitudinal study

OBJECTIVE: The purpose of this study was to describe the presence and impaction status of people's third molars at age 18 years, as well as the observed changes in their clinical status between ages 18 and 26 years. STUDY DESIGN: Eight hundred twenty-one participants in a prospective cohort study were dentally examined at ages 18 and 26 years, and panoramic radiographs were taken at age 18 years but not at 26 years. For each tooth, its radiographic impaction status at age 18 years was compared with the clinical status by age 26 years. RESULTS: Of the 2857 third molars assessed at age 18 years, 92.8% were able to be followed up clinically at age 26 years. Approximately 54.9% of the teeth that were not impacted by age 18 had erupted by 26 years. Of the teeth that were impacted by age 18, 33.7% had fully erupted by age 26, 31.4% had been extracted, and 13.1% remained unerupted. Of the maxillary teeth that were categorized as "impacted" at age 18 years, 36.2% had fully erupted by age 26, whereas only 25.6% of the mandibular teeth had done so (P <.01). Fewer mandibular teeth than maxillary teeth remained unerupted by the time the patient was 26 years old (27.4% and 41.4%, respectively; P <.01), but there was no significant difference between the jaws in the proportion of impacted teeth at age 18 years that had been extracted by age 26 years (29.6% and 30.3%, respectively). For mesioangularly impacted third molars, 39.3% of maxillary teeth and 20.4% of mandibular teeth had fully erupted by age 26. Of the third molars that were mesioangularly impacted at age 18 years, 39.3% of maxillary teeth and 20.4% of mandibular teeth had fully erupted by age 26 years, whereas almost one-third of each had been extracted. Of the distoangularly impacted third molars, 20.4% of the maxillary teeth and one-third of the mandibular teeth had erupted by age 26, with 21.6% of the maxillary teeth and 31.6% of the mandibular teeth having been extracted. CONCLUSION: Other than horizontally impacted third molars, a substantial proportion of other impaction types do erupt fully, and radiographically apparent impaction in late adolescence should not be sufficient grounds for their prophylactic removal in the absence of other clinical indications.     

Talon cusp associated with other dental anomalies: a case report

Talon cusp is an uncommon dental anomaly referring to an accessory cusp projecting from the cingulum area, or cemento-enamel junction of maxillary or mandibular anterior teeth, in both the primary and permanent dentition. This paper reports a rare case of talon cusp affecting the mandibular right central incisor and maxillary right lateral incisor, together with other dental abnormalities, viz. an inverted impacted migrating mandibular right second premolar; complete agenesis of the maxillary and mandibular third molars, the maxillary right second permanent molar, and the mandibular left permanent central incisor; severe crowding; deep bite; hypoplastic teeth; bilateral reverse cross-bite in the premolar region; and a retrognathic mandible. The presence of this number of dental anomalies in a single patient is rare.     

Remaining mandibular third molars in an adult population

summary Although tooth loss with age has been extensively investigated, there appears to be no literature on the relationship of age to remaining mandibular third molars. The study showed that as age increases so does the frequency of absent vertically erupted mandibular third molars. However, no correlation was found between age and loss of mandibular impacted third molars in men of 71 years of age or older. The evidence presented here suggests that impacted mandibular third molars, which have not been infected, may be more likely to remain compared with other teeth at potential risk.     

An adolescent patient with multiple impacted teeth

Multiple impacted permanent teeth is uncommon and rarely reported in the literature. This article reports the treatment of an adolescent patient with multiple impacted teeth without systemic disease. A 9-year 2-month-old boy complained of a delay of eruption of the first molars. All first molars were unerupted, and the left deciduous second molar was a submerged tooth. The panoramic radiograph showed all permanent teeth except the incisors were unerupted and, especially for the first molars, spontaneous eruption was not expected. His medical history was uneventful. A lingual arch appliance and a segmental arch were placed on the mandibular and maxillary dentitions, respectively, to guide eruption of the impacted first molars. After traction of the first molars, eruption of the impacted lower premolars was induced. Furthermore, at 15 years the impacted mandibular second molars were also positioned properly by use of the lingual arch with auxiliary wires. After achieving traction of the impacted teeth, tooth alignment was initiated using multibracket appliances after the bilateral extraction of the second premolars. After 22 months of treatment with multibracket appliances, an acceptable occlusion was achieved with a Class I molar relationship. After 2 years of retention an acceptable occlusion was maintained without any relapse in the occlusion. Since a delay in the treatment of impacted teeth may induce secondary problems such as root dilacerations and ankylosis, it is highly recommended to perform early treatment of multiple impacted teeth during adolescence.     

超声骨刀与涡轮法拔除下颌阻生第三磨牙的效果比较

目的: 比较超声骨刀和涡轮法拔除下颌阻生第三磨牙的手术时间和术后反应等,评价2种方法拔除不同类型下颌阻生第三磨牙的疗效。方法: 2018年1月—2019年1月宿迁市人民医院收治的120例中、低位埋伏阻生牙患者,按照垂直阻生、近中阻生、水平阻生各40例分为3组。每组20例应用超声骨刀,20例应用涡轮钻。记录手术时间、术后疼痛、肿胀、开口度及永久性神经损伤等严重并发症情况。采用SPSS 17.0软件包对数据进行统计学分析。结果: 术后1 d和3 d,超声骨刀法疼痛显著小于涡轮法;7 d时,2组之间疼痛无显著差异。垂直阻生组手术时间、术后肿胀、开口度在2组之间无显著差异。近中阻生牙组2种方法术后肿胀无显著差异,但超声骨刀法手术时间更短、开口度更大。水平阻生牙的手术时间、肿胀、开口度超声骨刀法优于涡轮法。各组均未出现严重并发症。结论: 超声骨刀对组织可选择性切割、截骨精准、术后创伤小、使用安全方便,在一定程度上比涡轮更具优势,真正实现了微创外科。临床上推荐应用超声骨刀拔除中低位近中或水平埋伏阻生牙,以减少术后创伤,提高手术疗效。     

Root canal configurations of third molar teeth. A comparison with first and second molars in the Turkish population

The purpose of the current study was to determine the similarities of maxillary and mandibular third molars with the other molar teeth. A total of 2016 extracted maxillary and mandibular permanent teeth were evaluated. The teeth were divided into six groups. The teeth were stored in 5% nitric acid solution for 7 days, then placed in increasing concentrations of ethyl alcohol. The teeth were rendered transparent by immersion in xylene solution for 4 days until complete transparency was achieved. Three roots were present in 93.0% of the maxillary molars, and 91.3% of the second molars. Among the maxillary third molars, 35.5% were single-rooted and 24.9% of the mandibular third molars had single roots. Double roots were present in 69.2% of the mandibular third molars, and 5.4% had three roots. Four new root canal configurations were encountered in this study. The root canal configurations of the mandibular and maxillary teeth showed similarities with the results of other studies performed in different populations.     

Surgical management of impactedthird molars

Teeth may become impacted when they fail to erupt or develop into the proper functional location. As such, impacted teeth are considered nonfunctional, abnormal, and pathological. The mandibular third molar is the most common tooth to become impacted. The cause of impacted third molars is thought to be inadequate space. Several studies indicate that a change from a coarse, attritive diet to a modern, refined diet has lead to an increased incidence of impacted teeth. Interproximal attrition allows for greater mesial migration of teeth and space for third molar teeth. Teeth that fail to attain a functional position may be pathological and should be considered for removal. The indications for removing impacted teeth can be divided into those of acute or chronic pathology. Impacted third molars are often associated with pain, infection, cyst formation, benign tumors, root resorption, bone loss, periodontal disease, and caries. The decision to surgically remove impacted third molars is often unclear. There are no absolute treatment protocols established. The dentist must consider a variety of factors and make an informed decision with the patient. Most experienced clinicians combine objective data and common sense to arrive at a logical treatment plan. The purpose of this article is to discuss factors related to impacted teeth and help the orthodontist understand the general management of impacted third molars. The decision for surgery will be assisted by an understanding of all of the risk factors associated with impacted teeth and presenting the options to the patient.     

Dentigerous cyst containing multiple impacted teeth: a rare case report

The dentigerous cyst is a developmental odontogenic cyst, which apparently develops by accumulation of fluid between reduced enamel epithelium and the tooth crown of an unerupted tooth. It is one of the most prevalent types of odontogenic cysts associated with erupted, developing, or impacted tooth, particularly the mandibular third molars, the other teeth that are commonly affected are maxillary canines. The present case report is unique as it enclosed three permanent maxillary teeth: the central incisor, lateral incisor, and canine that had to be extracted during surgical enucleation of the cyst.     

Two cases of molar root resorption

The presence of unerupted teeth in close proximity to adjacent teeth can cause root resorption. The third molars and mandibular premolars are the most frequent teeth to be impacted and the relationship between impacted teeth causing root resorption of adjacent teeth has been well documented, but it is surprising how few studies have analysed the incidence of root resorption in these cases. This paper discusses two patients who have undergone molar root resorption due to adjacent unerupted impacted teeth.     

基于锥形束CT的多生牙新分类方法临床意义研究

 目的　应用锥形束CT（cone-beam CT，CBCT）对多生牙进行新的临床分类，并分析新分类方法的临床意义。方法　收集2016-2019年首都医科大学附属北京友谊医院口腔科的CBCT影像资料5100例，其中多生牙患者209例，共计多生牙278颗。应用CBCT对多生牙进行新的临床分类，包括萌出型、骨埋伏高位型、骨埋伏低位型、骨埋伏复杂型和牙弓外型，并分析其临床意义。结果　（1）临床资料分析：多生牙发生率为4.1%，其中有1颗多生牙的患者占76.6%，有2颗多生牙的患者占19.1%，有3颗及以上多生牙的患者占4.3%。多生牙好发部位依次为：上颌切牙区、上颌磨牙区、下颌尖牙及前磨牙区、上颌尖牙及前磨牙区、下颌磨牙区。34.9%的多生牙对邻近恒牙产生了继发影响，以萌出错位及阻生为主，主要发生在上颌切牙区。（2）新分类方法的临床意义分析：上颌切牙区多生牙以骨埋伏低位型及萌出型为主，尖牙、前磨牙及磨牙区多生牙以萌出型为主。不同类型多生牙对邻近恒牙产生继发影响的发生率不同或不全相同（χ2 = 26.057，P < 0.001），提示对邻近恒牙易产生继发影响的多生牙类型依次为：萌出型、骨埋伏复杂型、骨埋伏高位型、牙弓外型、骨埋伏低位型。结论　基于CBCT的多生牙新分类方法简单实用，其中萌出型、骨埋伏复杂型及骨埋伏高位型多生牙更易产生错牙合畸形，建议尽早拔除多生牙、定期随访，必要时正畸治疗。     

The effect of attrition on the pre-Columbian Indian arch length

A statistically significant difference is shown between the mesiodistal crown diameters of unworn and worn permanent mandibular teeth of pre-Columbian Peruvian Indians. It would appear from the data presented that interproximal attrition prior to the emergence of the third molars could make space for the unimpeded eruption of these teeth. This is substantiated with data from previous studies where it was found that in this population those cultural groups with the highest attrition indices had the lowest incidences of impacted teeth while the culture with the lowest level of attrition had the greatest incidence of impacted teeth (Sawyer, 1977; Sawyer et al., 1978c). The relationship of these findings with a modern theory and technique of orthodontic treatment is noted.     

The etiology and prediction of mandibular third molar impaction.

1. Skeletal Class II dental base relationship with a shorter, narrower, more acute angled madible was found in association with impacted third molars, compared with erupted teeth. 2. These differences were found at age 18+ years but were less obvious at age 10 to 11 years. 3. There was a reduced amount of mandibular growth in impacted third molar cases. 4. There was a slight tendency for impacted third molars to be larger than those which erupted. 5. The presence of a space between second and third molars in the early stages of development is not an indication that the third molar will erupt. 6. The developmental angulation of the third molar to the mandibular plane was higher in the impacted third molar group. 7. Accurate prediction of third molar impaction from radiographic measurements is not possible at age 10 to 11 years.     

Second molar extractions: a review

In this exhaustive review, a number of parameters related to maxillary and mandibular second molar extractions are discussed. The parameters reviewed include the timing of extractions and the effect of extractions on third molar eruption, posterior interdigitation, and incisor imbrication. The advantages and limitations of this procedure are outlined. The available information strongly suggests that the extraction of second molars relieves crowding in the posterior part of the arch, causes faster eruption of third molars, and diminishes the number of unerupted and/or impacted third molars. Consideration of the decrease in the number of impacted third molars after second molar extraction should be balanced with the fact that the extracted teeth are usually sound and are unimpacted. In addition, the third molars that do erupt frequently are poorly angulated and/or in poor contact with the first molars. This will necessitate an additional "late" period of fixed-appliance therapy to bring these teeth into good occlusion.     

超声骨刀与凿骨劈冠法拔除下颌阻生智齿的比较

目的 探讨超声骨刀拔除下颌阻生智齿的效果.方法 根据下颌阻生第三磨牙拔除难度判断方案选择拔牙难度判断为较难的228颗下颌阻生智齿,分成实验组和对照组,每组114颗,实验组应用超声骨刀法拔牙,对照组采用凿骨劈冠法拔牙.对2组的拔牙时间、术后疼痛、张口受限、面部肿胀情况进行分析比较.结果 实验组平均拔牙时间为(16+5.2...     

阻生下颌第三磨牙2种拔除方法的比较

目的:比较拔除下颌阻生第三磨牙时,传统的凿骨劈冠法与改良涡轮机拔除法的优劣.方法: 600 例下颌阻生第三磨牙病例,其中300 例,使用传统的凿骨劈冠法拔除, 另300 例使用改良涡轮机法拔除,对手术时间以及术中、术后并发症进行对比观察和统计分析.结果: 2 种方法的手术时间分别为(22.285±12.025) min和(16.115±12.078) min.与传统的凿骨劈冠法相比,改良涡轮机拔除法拔除下颌阻生第三磨牙的手术时间较短(P<0.05),术中及术后并发症的发生率均明显降低(P<0.05).结论: 改良器械的应用,使阻生下颌第三磨牙的拔除更加方便,值得推广应用.